Milking cows vary substantially in their milk producing capabilities. The high producing cows are much more valuable than the low producers since they yield a greater quantity of milk than the low producers for the same quantity of feed and care. By monitoring the output of individual cows, the dairyman can identify his high and low producers and use this information to improve the quality of his herd by culling the low producers. It may also be possible to use this information to increase the volume of milk production per quantity of feed to the herd since evidence exists that the total milk production from a herd can be optimized by providing a larger amount of feed to the high producing cows than to the lower producers.
The daily monitoring of milk production from individual cows can also have benefits in addition to identifying the high and low producing cows. For example, a decrease in production from a particular cow over a short period of time may indicate that the cow may be sick before other, more obvious symptoms develop in the cow. The dairyman may also use the milk production records to determine the effect on milk production of different feeds or feed supplements, allowing him to choose the feeding regimen which will provide him with the lowest cost production. The monitoring of milk production from individual cows allows the feeding regimen to be even further refined, if desired, by choosing feeds and supplements which are best suited to achieve the optimum production from individual cows.
Several types of equipment are presently available for use in monitoring the output of cows during milking. The most common and simple apparatus is a glass milk jar which is connected to the milk line and which accumulates the milk from each cow. After milking of the cow is completed, the dairyman records the identity of the cow and reads the volume of milk contained within the jar by comparing the level of milk with indica etched in the glass, and thereafter opens a valve at the bottom of the jar to release the milk into a common milk line. While the apparatus involved is simple and relatively inexpensive, monitoring the milk in this manner requires a substantial amount of the dairyman's time and is subject to substantial measurement errors since the visual reading of the level of milk within the milk jar requires some judgment. Systems are also available which automatically monitor the milk flow from the cow using flow meters of various designs, typically of the rotating vane or cup type. In the simplest of these systems, the meters provide a visual display to the milking machine operator of the volume of milk that is passed through the meter, and the operator then manually records the milk volume and the identity of the cow from which the milk was taken. More complex and automated systems may require only that the operator log in the identity of the cow being milked on a keyboard, with the measured milk volume and the cow's identity being automatically recorded on a remote printout or stored for further processing in a microcomputer. Automatic cow identification systems are also available, and the identity of the cow so monitored may be correlated with the milk volume monitored by the milk meter and this information may be either recorded immediately or stored in a microcomputer for processing.
Some disadvantages have been noted with the use of flowmeters to measure milk production. When used to measure milk flow directly from a cow, flowmeters can be subject to measurement errors, in part because of the intermittent nature of the milk flow and the mixing of air with the milk. Because the milk is passed directly from the flowmeter to a common milking line, it is not possible for the dairyman to manually verify the measurements obtained from the flowmeters. Flow measuring devices generally have rotating and moving parts which are naturally subject to wear and breakdown over time. Currently available flowmeters typically also use electrical signaling, so that a low voltage electrical wire must be run into the milking parlor to the flowmeter at a position close to the cow. The potential thus exists for short circuits and ground leakage of the currents in the electrical signaling lines, particularly in the damp environment of the milking parlor. These stray currents may possibly be conducted to the cow, potentially irritating the cow and interfering with milk production.